DETROIT, Aug 6 (Reuters) - Amid concerns that Fiat shareholders will prevent a merger of the Italian automaker with Chrysler Group, the American automaker reported that second-quarter profit was up 22 percent to $619 million.

Fiat shares fell as much as 8.5 percent on Wednesday to their lowest of the year on concerns that investors who voted against the merger with Chrysler would exercise their right to sell the stock, potentially jeopardizing the tie-up. .

Sergio Marchionne, chief executive officer of both Fiat and Chrysler, will speak to industry analysts on a conference call to begin at 11 a.m. EDT (1500 GMT) on Wednesday.

Marchionne wants to incorporate the two carmakers as a Dutch-registered combine, Fiat Chrysler Automobiles (FCA), paving the way for a U.S. listing which it hopes will help fund an ambitious turnaround plan.

But the merger is still subject to some conditions, including a limit on the number of dissenting shareholders who exercise their right to sell out.

A research note from Barclays said that in its view it would “be quite tough to reach the threshold” of shareholders to prevent the merger.

Chrysler posted a rise of 14 percent in net revenue to $20.5 billion.

Chrysler also confirmed its full-year outlook given previously that includes adjusted net income between $2.3 billion and $2.5 billion on net revenue of about $80 billion.

When Fiat issued its second-quarter results last week, Marchionne said it would review its practices for leasing and sales in North America in order to boost margins. In the year’s first half, Marchionne said, launch costs impaired Chrysler’s and Fiat’s margins. There are no major launches in the second half of the year for Chrysler.

Fiat executives have indicated that European auto sales were gradually improving, which was confirmed on Wednesday when LMC Automotive said sales in Western Europe rose 5 percent in July.

Fiat shares were down 5 percent at 6.51 euros. (Additional reporting by Agnieszka Flak in Milan and Ben Klayman in Detroit; Editing by Grant McCool)